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Measurement of dynamic fracture toughness and failure behavior for explosive mock materials

Pengwan CHEN, Zhongbin ZHOU, Shaopeng MA, Qinwei MA, Fenglei HUANG

《机械工程前沿（英文）》 2011年第6卷第3期页码 292-295 doi: 10.1007/s11465-011-0237-8

摘要：

In this work, a pre-cracked semi-circular shaped explosive simulant was loaded using a split Hopkinson pressure bar (SHPB). A high-speed camera was used to capture the deformation and fracture process of the specimen in situ. The digital images were processed using the digital image correlation (DIC) method. Next, full displacement and strain fields were obtained. The displacement vector field shows that the specimen fractured under tensile stress action. The strain field can be used to predict the crack propagation. Results show that the method of combined DIC and SHPB is effective to study the dynamic deformation and fracture behavior of explosive simulants. In addition, the specimen was loaded using a drop weight. The fracture toughness of the specimen was preliminary measured.

关键词： digital image correlation polymer bonded explosive simulant split Hopkinson pressure bar (SHPB) semicircular bending test deformation fracture toughness

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Recent development in low-constraint fracture toughness testing for structural integrity assessment of

Jidong KANG, James A. GIANETTO, William R. TYSON

《机械工程前沿（英文）》 2018年第13卷第4期页码 546-553 doi: 10.1007/s11465-018-0501-2

摘要：

Fracture toughness measurement is an integral part of structural integrity assessment of pipelines. Traditionally, a single-edge-notched bend (SE(B)) specimen with a deep crack is recommended in many existing pipeline structural integrity assessment procedures. Such a test provides high constraint and therefore conservative fracture toughness results. However, for girth welds in service, defects are usually subjected to primarily tensile loading where the constraint is usually much lower than in the three-point bend case. Moreover, there is increasing use of strain-based design of pipelines that allows applied strains above yield. Low-constraint toughness tests represent more realistic loading conditions for girth weld defects, and the corresponding increased toughness can minimize unnecessary conservatism in assessments. In this review, we present recent developments in low-constraint fracture toughness testing, specifically using single-edge-notched tension specimens, SENT or SE(T). We focus our review on the test procedure development and automation, round-robin test results and some common concerns such as the effect of crack tip, crack size monitoring techniques, and testing at low temperatures. Examples are also given of the integration of fracture toughness data from SE(T) tests into structural integrity assessment.

关键词： fracture toughness constraint effect single-edge-notched tension test pipeline structural integrity assessment

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A toughness based deformation limit for X- and K-joints under brace axial tension

Bo GU,Xudong QIAN,Aziz AHMED

《结构与土木工程前沿（英文）》 2016年第10卷第3期页码 345-362 doi: 10.1007/s11709-016-0333-2

摘要： This study reports a deformation limit for the initiation of ductile fracture failure in fatigue-cracked circular hollow section (CHS) X- and K-joints subjected to brace axial tension. The proposed approach sets the deformation limit as the numerically computed crack driving force in a fatigue crack at the hot-spot location in the tubular joint reaches the material fracture toughness measured from standard fracture specimens. The calibration of the numerical procedure predicates on reported numerical computations on the crack driving force and previously published verification study against large-scale CHS X-joints with fatigue generated surface cracks. The development of the deformation limit includes a normalization procedure, which covers a wide range of the geometric parameters and material toughness levels. The lower-bound deformation limits thus developed follow a linear relationship with respect to the crack-depth ratio for both X- and K-joints. Comparison of the predicated deformation limit against experimental on cracked tubular X- and K-joints demonstrates the conservative nature of the proposed deformation limit. The proposed deformation limit, when extrapolated to a zero crack depth, provides an estimate on the deformation limits for intact X- and K-joints under brace axial loads.

关键词： circular hollow section (CHS) tubular joint fracture failure deformation limit J-integral

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Micromechanics model for static and dynamic strength of concrete under confinement

ZHENG Dan

《结构与土木工程前沿（英文）》 2008年第2卷第4期页码 329-335 doi: 10.1007/s11709-008-0044-4

摘要： The process of propagation, kinking of micro-cracks in concrete and the interaction among cracks as well as the induced failure were analyzed using the model that describes the wing type crack from the point of view of micromechanics. The pseudo-force method is applied to calculate the compressive strength factor of kinky propagated crack taking into account the effect of interaction among cracks. On the assumption that the micro fracture toughness of concrete does not vary with stain rate, the static and dynamic strength of concrete under different confinements can be calculated. The comparison of calculation result with experimental data indicates that a good agreement is achieved which implies that the model can be used to explain the rate-dependent properties of concrete in multi-axial stress state.

关键词： comparison different interaction pseudo-force toughness

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Effect of fiber hybridization on energy absorption and synergy in concrete

Ahmadreza RAMEZANI, Mohammad Reza ESFAHANI

《结构与土木工程前沿（英文）》 2019年第13卷第6期页码 1338-1349 doi: 10.1007/s17009-019-0558-2

摘要： In the present study, steel and polypropylene (PP) fibers have been utilized with the intent of obtaining hybrid fiber-reinforced concrete (HFRC) with desirable mechanical properties. An attempt has been made to scrutinize the properties of HFRC with the main concentration being on energy absorption characteristics of concrete and the efficacy of fiber hybridization in producing synergy. Accordingly, a total of 180 specimens, representing 20 different mixtures have been cast and evaluated through compressive, split tensile, and flexural tests. The relevant flexural toughness of the specimens was calculated using ASTM C1018, ASTM C1609, JSCE, and PCS methods, and the effectiveness of these methods was evaluated based on the experimental results. It was observed that steel fibers are more effective in the improvement of flexural toughness in the presence of PP fibers. Furthermore, synergy associated with the combination of fibers at different stages of deflection of the beam specimens was observed and analyzed.

关键词： hybrid fiber-reinforced concrete synergy toughness steel fibers polypropylene fibers

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混凝土的裂缝与控制

缪昌文,刘建忠,田倩

《中国工程科学》 2013年第15卷第4期页码 30-35

摘要：

在分析混凝土开裂的危害和产生原因的基础上，提出裂缝控制新技术。采用双亲性单分子膜，减少混凝土早期的水分蒸发，抑制混凝土早期因失水太快而产生的塑性收缩裂缝；采用减水与减缩共同作用，控制混凝土壳体及薄壁结构的早期开裂；采用调控水泥水化过程中的放热量，提高大体积混凝土的温控能力；采用遥爪聚合型增韧剂，增加混凝土的韧性，减少混凝土的脆性开裂。

关键词：混凝土裂缝收缩水化热韧性

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Carbonized nano/microparticles for enhanced mechanical properties and electromagnetic interference shielding of cementitious materials

Rao Arsalan KHUSHNOOD,Sajjad AHMAD,Luciana RESTUCCIA,Consuelo SPOTO,Pravin JAGDALE,Jean-Marc TULLIANI,Giuseppe Andrea FERRO

《结构与土木工程前沿（英文）》 2016年第10卷第2期页码 209-213 doi: 10.1007/s11709-016-0330-5

摘要： In the present work, carbon nano/microparticles obtained by controlled pyrolysis of peanut (PS) and hazelnut (HS) shells are presented. These materials were characterized by Raman spectroscopy and field emission-scanning electron microscopy (FE-SEM). When added to cement paste, up to 1 wt%, these materials led to an increase of the cement matrix flexural strength and of toughness. Moreover, with respect to plain cement, the total increase in electromagnetic radiation shielding effect when adding 0.5 wt% of PS or HS in cement composites is much higher in comparison to the ones reported in the literature for CNTs used in the same content.

关键词： carbon nano/microparticles green cement toughness mechanism electromagnetic shielding effect

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Advanced cement based nanocomposites reinforced with MWCNTs and CNFs

Emmanuel E. GDOUTOS,Maria S. KONSTA-GDOUTOS,Panagiotis A. DANOGLIDIS,Surendra P. SHAH

《结构与土木工程前沿（英文）》 2016年第10卷第2期页码 142-149 doi: 10.1007/s11709-016-0342-1

摘要： Cementitious materials reinforced with well dispersed multiwall carbon nanotubes (MWCNTs) and carbon nanofibers (CNFs) at the nanoscale were fabricated and tested. The MWCNTs and CNFs were dispersed by the application of ultrasonic energy and the use of a superplasticizer. Mechanical and fracture properties including flexural strength, Young’s modulus, flexural and fracture toughness were measured and compared with similarly processed reference cement based mixes without the nano-reinforcement. The MWCNTs and CNFs reinforced mortars exhibited superior properties demonstrated by a significant improvement in flexural strength (106%), Young’s modulus (95%), flexural toughness (105%), effective crack length (30%) and fracture toughness (120%).

关键词： multi-walled carbon nanotubes carbon nanofibers mortars toughness Young’s modulus

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Flexural behavior of ECC hollow beams incorporating different synthetic fibers

Ahmmad A. ABBAS, Farid H. ARNA ’OT, Sallal R. ABID, Mustafa ÖZAKÇA

《结构与土木工程前沿（英文）》 2021年第15卷第2期页码 399-411 doi: 10.1007/s11709-021-0701-4

摘要： Twelve ECC beams with three different fiber types, along with four normal concrete beams, were tested in this study to evaluate the influence of cross-sectional hollowing on their flexural performance. The fiber types used were nylon monofilament (NM), low-cost untreated polyvinyl alcohol (PVA), and polypropylene (PP). Three different square hole sizes of 60, 80, and 100 mm with cross-sectional hollowing ratios of 0.16, 0.28, and 0.44, respectively, were adopted for each group of beams in addition to a solid beam. All beams were tested under four-point loading using a displacement-controlled testing machine. The test results showed that ECC beams can mostly withstand higher cracking and ultimate loads compared to their corresponding normal concrete versions. The results also showed that both the ductility and toughness of the ECC beams are higher than those of the normal concrete beams and that the ductility values of the hollow beams with a hole size of 60 mm are higher than those of the corresponding solid beams. Moreover, hollow ECC beams with hole sizes of 60 and 80 mm exhibited a higher ductility than a solid normal concrete beam.

关键词： hollow beam hollowing ratio ECC flexural strength ductility toughness

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Feasibility analysis of modified AL-6XN steel for structure component application in supercritical water-cooled reactor

Xinggang LI, Qingzhi YAN, Rong MA, Haoqiang WANG, Changchun GE

《能源前沿（英文）》 2009年第3卷第2期页码 193-197 doi: 10.1007/s11708-009-0030-0

摘要： Modified AL-6XN austenite steel was patterned after AL-6XN superaustenitic stainless steel by introducing microalloy elements such as zirconium and titanium in order to adapt to recrystallizing thermo-mechanical treatment and further improve crevice corrosion resistance. Modified AL-6XN exhibited comparable tensile strength, and superior plasticity and impact toughness to commercial AL-6XN steel. The effects of aging behavior on corrosion resistance and impact toughness were measured to evaluate the qualification of modified AL-6XN steel as an in-core component and cladding material in a supercritical water-cooled reactor. Attention should be paid to degradation in corrosion resistance and impact toughness after aging for 50 hours when modified AL-6XN steel is considered as one of the candidate materials for in-core components and cladding tubes in supercritical water-cooled reactors.

关键词： supercritical water cooled reactor tensile impact toughness corrosion aging

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高强度厚规格海洋平台用钢研究进展及应用

刘振宇,周砚磊,狄国标,王国栋

《中国工程科学》 2014年第16卷第2期页码 31-38

摘要：

随着石油工业的不断发展，海底油气开发已经逐渐从浅海大陆架延伸至深海域，在降低成本的基础上，保证厚规格钢板的高强度高韧性以及抗层状撕裂性能是未来海洋平台用钢的发展方向。本文介绍了国内外高强度海洋平台用钢的研究现状，分析了此类钢板生产亟需解决的关键技术难题，阐述了东北大学轧制技术及连轧自动化国家重点实验室（RAL）近年来在高强度厚规格海洋平台用钢研究领域的工作以及工程应用情况。

关键词：海洋平台用钢低温韧性超快速冷却颈缩裂纹扩展

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我国航空铝合金产业发展战略研究

熊柏青,闫宏伟,张永安,李志辉,李锡武

《中国工程科学》 2023年第25卷第1期页码 88-95 doi: 10.15302/J-SSCAE-2023.01.005

摘要：

航空铝合金作为航空器机体结构中最重要的结构材料之一，是我国国防科技工业发展、现代化经济体系建设、深入实施制造强国战略的重要物质基础。当前国际上已发展形成高强高韧铝合金、高比强/高比模铝合金、含钪高性能铝合金等三类主要航空铝合金体系，新一代高性能合金研究、高灵活度制备加工以及数据驱动的高效合金设计是主要的发展趋势。当前我国航空铝合金产业与国际发达国家总体“并跑”、部分“跟跑”，特别是在日趋复杂的国际国内宏观形势下，发展机遇与挑战并存，自主创新能力难以支撑航空铝合金材料创新引领、部分品种材料及装备“卡脖子”问题突出、产品国际市场竞争力不足、测试和应用数据积累及过程管控等基础体系能力短板尚存等问题更为突出。需从航空铝合金材料竞争力提升、新材料研发先行、高效上下游合作研发、新材料应用推广、材料指标和应用指标评价体系建立等方面发力，提升我国航空铝合金产业创新发展水平。

关键词：航空；铝合金；高强高韧；高比模量

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高钢级钢管和高压输送：我国油气输送管道的重大技术进步

李鹤林,吉玲康,田伟

《中国工程科学》 2010年第12卷第5期页码 84-90

摘要：

近年来，我国管道企业和相关科研院所联合攻关，取得了一批关键技术成果，这些成果包括：研制了X70，X80钢级高性能管线钢及焊管、管件；突破国际上螺旋缝埋弧焊管的使用禁区，确立了具有中国特色的“大口径高压输送主干线螺旋埋弧焊管与直缝埋弧焊管联合使用”的技术路线；在国内首次研究了高压输气管道动态断裂与止裂问题，采用Battelle双曲线模型预测了西气东输和西气东输二线等管道延性断裂的止裂韧性；在国内首次研究了油气管道基于应变的设计方法，解决了该设计方法及抗大变形管线钢管在强震区和活动断层管段应用的技术难题；解决了高强度焊管的腐蚀控制和应变时效控制等技术。

关键词：油气管道管线钢螺旋缝埋弧焊管止裂韧性基于应变的设计